Electric controlling apparatus



Mwah 3091943. F. @LOGAN f n 2,315,264

ELECTRIC CONTROLLING APPARATUS l f FiledKApril-zl, i939 2 sheets-sneer 1 Mmm KfJ/M/ 5y MQUATTQFQNEY n F. G. LOGAN ELECTRIC CONTROLLING APPARATUS y Mach 30, 1943.

` 2 sheets-sheet 2 Filed April 21, 1939 INVENTOR Patented Maru 3 idg 2,315,264 ELECTRIC CONTROLLING APPARATUS Frank G. Logan, Mount Vernon, N. Y., assigner to Ward Leonard Electric Company, a corporation of New York Application April 21, 1939, Serial No. 269,100 1 anims. (ci. mmm) This invention relates to an improved controlling apparatus and method of control, being particularly applicable for the purpose oi changing the voltage applied to a consumption circuit over a Wide range, such as in dimmer control of lighting circuits and the like. The invention is applicable tb an auto-transformer connected to a. supply circuit and wherein the voltage applied to the consumption circuit is changed by adjustment of the movable contact over the turns of the auto-transformer, althoughy the invention is applicable to other forms of inductive windings and to other variable voltage devices.

This invention covers improvements over the inventions disclosed and claimed in my United States Letters Patent #2,189,507 granted February 6, 1940, as regards certain features hereof and includes other features applicable to other :forms of controlling apparatus.

One object of the invention is tov provide an improved form of variable voltage controlling apparatus which will have the advantages re ferred to in' my said prior application and be of a compact and simple form of construction and which will be dependable under long continued use. Another and important object is to provide an improved form of apparatus whereby the voltage of the consumption circuit may be con trolled as desired over a wide range from a location remote from the apparatus and secure ad- 3@ justment thereof to any desired position for maintainingv any desired voltage on a consumption circuit and for increasing and decreasing it at will to any other desired voltage. Another ob ject is to provide apparatus whereby the change 35 in voltage of the consumption circuit may be made step by step in small amounts, or over a wide range, or in any way desired from. a remote point of control. Another object is to provide a simple means of control at the remote point and 40 of a type which will indicate by its position the relative value of the voltage applied to the conn sumptlon circuit. Other objects and advantages of the invention will be understood from the following description and accompanying drawings which illustrate a preferred embodiment.

Fig. l is a side elevation, partly in section; Fig. 2 is an inside elevation of the front portion oi.' the apparatus removed from the auto-transn former; Fig. 3 is an enlarged horizontal section through the middle of the movable contact carriage; Fig. 4 is a side view of a portion of the inductive windings showing the relation or the 5 movable contacts.

the relative position of the contacts thereon; and Fig. 5 is a diagram of parts and connections.

Referring to Fig. 1, a laminated core l is shown at the left-hand side which carries a winding 2 on one leg of the core. This winding is formed so as to provide two paths of exposed portions of the winding on its face 3, the two paths being indicated at 3a and 3b in Fig. 4. This winding is formed as described in my said prior patent in a manner t0 provide sequential contact of the movable contacts over the two paths Without short-circuiting any turn or turns of the winding and without breaking the continuity of the load circuit. Referring to Fig. 4 a portion of the turn of the winding is exposed to form a contact surface at 4. This turn then continues to the right and is embedded below a strip of insulation la. The turn then continues around the sides and back of the winding and reappears at the left of Fig. 4 under a. strip of insulation 4b. It then rises to form an exposed contact surface at 4c, from which it continues around the sides and back of the winding and reappears at the left to form an exposed contact portion 4d. The tum then continues to the right under insulation 4e, then again around the back and reappears at the left under the strip of insulation if and then continues to the right of Fig. 4 rising to form an exposed contact portion 4g and so on from one end of the winding to the opposite end. The cross section of the conductor of this winding may be round, square, rectangular, or oi other form and may be wound edgewise, it being important to provide ample and uniform exposed Contact surfaces. The winding is rst formed in the manner described with a1- ternate raised and depressed portions, the recesses formed by the depressed portions being filled in with insulating material, and then the contact side of the winding is ground down so as to expose the contact portions of the windings and to provide the two smooth paths of alternate contact and insulating portions staggered in relation to each other for engagement by the At the upper end of the autotransformer core are three contacts 5 mounted upon an insulating block 6 by which connection of the terminals of the Winding andof the movable contact may be made to the external circuits.

A supporting frame is mounted upon the core l and secured thereto by bolts l. This frame is composed of hollow rectangular end pieces 8, 8a made of sheet iron, these end pieces being conexposed portions of the turns of the windings and to nected together by a pair of vertically extending angle irons 3 which, together with the end pieces 3, 3a, form the main support for the controlling apparatus.

A long screw shaft IU extends vertically and centrally in front of the winding 2 and is supported at the upper end in a bearing Illa which is held in fixed position by metal angular strips il on the upper portion of the end piece 8. The lower end of the screw shaft is supported in a bearing lUb which is similarly supported by angular strips l I a which are secured to and extend from the lower end piece 8a, At the upper end of the screw shaft is fixed a gear I2 which is driven by a spur gear I2a fixed to .the shaft of a reversible motor I3. This motor is supported by the end piece 8 and may be of any type, such as a self-starting series motor with two ileld windings wherein the current may be relatively reversed for the purpose of driving the spur gear I2a in opposite directions and thereby drive the screw shaft lo in one direction or the other ac cording to the action imposed by the controlling apparatus. rl'he lower end I4 of the screw shaft is threaded with a much finer pitch than that of the main portion and carries a traveling nut Ita. Secured to this nut is an insulating strip I5 which extends forwardly and carries on its opposite sides a pair oi' yieldable contacts I6, idc. These contacts are located on opposite sides of a metal disk i1 which is secured to the lower end of a plunger I8 of a solenoid magnet having a winding Ita. This magnet is supported by angular end plates b which are in turn secured to the angle irons 9.

When the plunger I8 rises, contact is made by the disk Il with the upper contact I6 and when the plunger moves downwardly, the disk engages contact ia. A block of insulating material I3 having upper and lower inwardly projecting portions ISa is shown secured by a bolt ISb to the iront portion of the end plate I8b of the solenoid. The projections of this insulating block limit the upper and lower positions of the disk Il, an adjustable screw iic being located in the lower projection for adjustment of the limiting lower position of the disk I1. Above the solenoid and mounted on the angle irons 9 is a. pair of eondensers 23; and above them is similarly mounted a pair oi reactors 2l. The purpose of these will be hereinafter explained.

A pair of U-shaped rails 22 extend vertically the length of the apparatus with their side arms extending inwardly, as shown in Figs. 2 and 3. These rails are insulated from the frame support and have their ends xed to cross strips 23 of insulating material. The lower insulating strip 23 is shown at the lower portion of Figs. 1 and 2 and is of angular form and is secured to the angular strips Ela. The upper insulating strip 23 is secured between the side portions of the upper end piece 3. These rails form the guides for the movable carriage and also as conductors or" current from the movable carriage contacts to other parts of the apparatus.

The traveling carriage, as shown in Figs. 1, 2 and 3, is composed of a block 23 of insulating material. A -pair of Contact plates 24 of brass, or other suitable material, are interposed between the block 23 and the rails 24. As shown in Figs. l and 3, one of the plates 24 is provided with outwardly turned ends 24a which engage opposite sides of one of the arms of one of the rails 22. These outwardly turned ends serve to guide the movable carriage and keep the parts in alignment.

The insulating block 23 has an inwardly extending portion through which a central 1ongitudinal opening is formed for permitting the screw shaft I0 to pass freely through it. At the upper andlower ends of the block 23 are inwardly extending plates 25, the inner edges of which have threaded engagement with the screw shaft III. These are spaced slightly from the block 23 and are connected together by a metal strip 26 as shown in Fig. 3. A screw 21 is iixed to the middle of the front ot the block 23 and passes freelyA through an opening in the plate 23. A spring 28 envelops the shank of this screw and engages the plate 24 at its inner end and is retained under compression at its outer end by a.

washer 29`whlch in turn is retained by a pin 29a.

The spring 23 not only serves to press the threaded end plates 25 into engagement with the screw shaft I3 for insuring proper engagement but also serves to force the block 23 and contact plates 24 outwardly against the inner edges of the rails 22 for insuring good electrical contact therewith.

The connection between the rails 22 and the exposed `portions of the winding 2 is brought about by the provision of movable metal contact carriers 30 in the form of blocks. The upper end of one oi these blocks carries a. pair oi' contacts 3I, 32 which engages the exposed portions of the winding 2 in one of the paths 3a while the other block 33 similarly carries a pair of contacts 33, 34 which engages the other path 3b of the exposed portions of the winding. 'Ihese contacts are in the form of iiat plates which engage the paths of the windings endwise and are secured to the blocks by screw bolts 35, as shown in Fig. 2. Flexible leads of at braided copper wire connect the contacts to the plates 24 which engage the contact rails for providing additional electric connection. Each of the plates 24 have a pair of inwardly bent tongues 31, as shown ln Figs. 1 and 3, which yproject freely within a longitudinal slot in each of the contact blocks 33 for the purpose oi guiding and properly positioning the contacts. The ends of these slots are closed so that the tongues 31 bear against the closed ends of the slots for preventing endwise movement of .the contact blocks with reference to the movable carriage. 'Ihe upper tongues 31 of each block are respectively encircled by springs 33 which are interposed between the contact blocks 33 and the yplates 24 for the purpose of imposing proper and uniform pressure of the contacts against the exposed portions of the winding 2 and likewise serve to press the plates 24 against the contact rails 22. The lower end of each contact block 3B carries a strip 33 of insulating material secured in place by the screw bolts 35. These strips each have a central inwardly projecting portion 39a, as shown in Fig. l, which respectively engage the contact paths of the winding for guiding and maintaining the lower ends o1' the contact blocks 30 in proper position.

The pairs of contacts 3I, 32 and 33, 34 are shown in Fig. 4 in their relative positions in their engagement with the two paths of the winding and with the respective conducting and insulating portions of these paths. The two contacts 3| and 34 are made of good conducting material, such as copper or preferably of silver, or an alloy of silver, owing to their better withstanding the effects of arcing, while the two contacts 32 and 33 are formed of higher resistance contact material, such as carbon. As shown in Fig. 4, the upper edge of the contacts 32, 33 are slightly in advance of the upper edge of the contacts 3I, 34. This relative relationship of the contacting load circuit, beforevthe other contacts; and should break contact with the contacting portions of the winding when moving in the opposite direction after the contacts 3|, 34 of lower resistance material cease to engage the contact portions of the winding. Furthermore the total thickness of each pair of contacts is less than the width of the insulation between the contacting portions of the windings; and the staggered relation is such that when one pair of contacts is in full engagef ment with a contact portion, such as the lefthand pair with 4d in Fig. 4, the other pair of contacts is in engagement with an insulating portion, such as 4e, and is not in engagement with any contact portion at that time.

When the contact carriage is moved by the turning of the screw shaft i0, it is apparent that thev contacts will be simultaneously moved from the position shown in Fig. 4 toa position where both pairs of contacts will simultaneously engage contact portions of the windings in their respective paths; and then the right-hand pair of contacts will next be in full engagement with a contact portion, such as 4c while the other pair of contacts will be out of engagement with any contact portion and will rest upon the insulation 4b; and as the motion is continued, the pairs of contacts respectively make joint engagement with their Contact portions, then sole engagement by one pair of contacts, then joint connection of the pairs with their respective contact portions, then sole connection by the other pair of contacts and so on The diagram of Fig. 5 shows the connections of the parts. An alternating current source 40 is shown supplying the distribution lines 4|. The auto-transformer winding 2 is shown connected across these lines by the leads 42. The contact rails 22 are connected by leads 43 through a pair of reactive windings 44 to one side of the connu sumption circuit 45, the other side of which is connected to the upper supply line M which is the same line to which the upper end of the auto-transformer winding 2 is connected. The translating devices are indicated as lamps lid con-- nected across the consumption circuit but may be any other device to which a variable voltage is supplied by this apparatus. The core 4l upon which the reactive windings 4d are wound is shown as a three-legged core having the windings on their outside legs. The flux of these windings 44 is substantially independent of each other and are wound and connected so that the return path4 for the flux of each winding is through the central leg of the core. In fact this core may be divided centrally without materially ail'ecting the operation and .is shown as a three legged core for convenience in making. lt is important that these reactor' windings and their cores should function with substantial independence of each other. These windings and cores" correspond to the reactors 2i indicated in Figl l. of the drawings. An impedance device 5d is connected between the rails-22 and may be in the form of a non-inductive strip of resistance material bridging the rails, as indicated in Fig. 3. 75

This serves as a shunting impedance to the terminals of the reactive windings 44.

A'pair of leads 48 extend from the supply lines to the primary winding of a transformer 49, the secondary of which supplies a comparatively low voltage to the solenoid winding i3d. The circuit of this winding includes anadlustable rheostat 50 which may be located at any remote point for controlling the operation of the apparatus and the application of any desired voltage to the consumption circuit 45. The disk I1 of the plunger is electrically connected by a flexible lead 5l to `one side of the supply line; and the contacts I6,

|6a are respectively connected by the leads 52 to the reversible field windings of the motor I3, from which a common return 53 is connected to the opposite side of the lines lll from that to which the lead 5i is connected. The condensers 20 are respectively connected across the windings of the motor for bringing the power factor of the motor circuit to unity, or nearly so, so as to reduce the amount of the current required by the motor and thereby reduce the value of the current necessarily carried by the contacts I6, iSd when engaged with the contact disk I1. This also reduces the arcing upon interruption of the motor circuit at the contacts.

It is apparent that when the contact carriage is in any selected position, the voltage applied to the consumption circuit will depend upon the number of turns of the auto-transformer winding included in series with the consumption circuit. This circuit may be followed from the lower supply line 4| to the lower end of thewinding 2, and through a portion of this winding `in the solenoid winding IBa; and the value of this current determines the position of the plunger i8 and contact disk Il.

In the position of the parts shown in Fig. 5, the arm of the rheostat 50 is in an intermediate position and the plunger I8 and contact disk l arenmaintained in about mid-position. This gives an approximately mid-position of the contact carriage and an application of voltage to the load circuit of about one-half of that of the source 40. If it be desired to decrease the voltage applied to the consumption circuit, the arm of the rheostat 5G is adjusted to remove-more resistance from the circuit and thereby somewhat raise the plunger i8. This brings the disk il into engagement with the contact I6 which completes a circuit through the controlling rnotor in such direction as to cause the Contact carriage to be moved upwardly. This motor circuit rnay be traced from the upper line 4i by lead 53 through the motor i3 and its upper eld winding and thence to the contact i6, disk il and lead 5l to the lower line lll of the supply circuit. The turning of the screw shaft by lthe motor in a direction to raise the Contact carrier likewise causes the traveling nut Ma on the lower end of the shaft to move upwardly and thereby raise its contacts i6, Ia a vertical vdistance which is proportionately much less than the extent of travel of the contact carriage, the

relative movement being determined by the ratio of the pitch of the screw shaft l0 and of its extension i4. This action continues until the contact l5 is moved sufficiently to break its engagement with the disk ll. This interrupts the motor .circuit and stops the movement of the parts; andthe voltage applied to the consumption circuit will be dependent upon the position to which the movable contact of the rheostat 5B has been moved. It it be desired to further decrease the voltage applied to the load circuit Eincluding additional turns of the auto-transormer winding in series in the load circuit across the supply lines ll, the contact of the rheostat 50 is moved to cut out additional resistance from the circuit of the solenoid winding |8a. The resultant increase of current therein will raise the disk Il to again engage the contact I6. This again starts the controlling motor in the same manner and in the same 'direction as before which raises the contact carriage to include more turns of the auto-transformer in series in the load circuit and thereby lower the voltage applied thereto. This action continues until the contact I6 again breaks connection with the disk i7 which stops the motor. In this way, by ad- Justment of the rheostat 50, the contact carriage may be brought to its uppermost position when approximately no voltage of the supply lines will be applied to the load circuit. At this time the disk I1 engages the upper projection |9a which serves as mechanical means for limiting the upper movement of the disk Il and thereby also serves as a safety device to prevent current from being supplied to the controlling apparatus after it has reached its limiting position in one direction. v

When it is desired to increase the voltage applied to the load circuit the rheostat 50 is adjusted to decrease the current in the solenoidwinding I8a which permits the disk l1 tmove,

to a lower position and engage the contact lqf" This closes a circuit from the upper supply line il through the motor I3 and its lower eld winding, thence to the contact 15a, disk ll, and by lead 5l to the lower supply line 4l. The motor then turns the shaft lll in the opposite direction and causes the contact carriage to move downwardly to increase the voltage applied to the consumption circuit and at the same time causes the traveling nut Ha to move downwardly until the contact l6a breaks connection with the disk l'l. This stops the movement of the motor; and the voltage applied to the consumption circuit remains at a lxed value until further adjustment of the rheostat 50. It is evident that if this rheostat be adjusted to further reduce the current in the solenoid winding |8a, the voltage applied to the load circuit will be correspondingly increased and when the disk il has been brought against the lower stop lila, the limiting position is reached and substantially full voltage is applied to the consumption circuit.

Thus it is apparent that by merely adjusting the rheostat 50, the voltage applied to the consumption circuit may be raised or'lowered from any value to a desired Value. If it be desired to pass from a very high voltage to a very low voltage, tho rheostat may be adjusted to a position corresponding with the desired low voltage. The disk l'I is then raised and pressed against the contact i8 by the upward pull of the solenoid plunger, the disk being maintained in engagement with the contact i6 as the latter moves upwardly until the plunger assumes the position corresponding to the adjustment of the rheostat. The contact I6 is then permitted to break congarages nection with the disk and the parts come to rest at the desired low voltage. Similarly the voltage may be increased from a low voltage to a high voltage by a continuous movement of the contact carrier until its position corresponds to that selected by the adjusted position of the rheostat.

Another important feature of the invention is that in the control of a lamp circuit for example, the lights may be dimmed or brightened very gradually and smoothly to give a change of lighting effects in a desired manner and at a desired rate of change without perceptible ilickering of the lighting. This is due to the fact that the control may be accomplished by a series of successive small changes which are rapid enough to avoid perceptible ickering ell'ects. The solenoid may be made sensitive in its response to small voltage differentials as determined by adjustment of the controlling rheostat il. When the latter is moved slowly over a desired range of movement, a small change of voltage' causes the plunger o1' the solenoid to move and make contact at its disk and the motor starts. It then advances the contact carriage only a small distance and then breaks the contact at the disk and stops the motor. The continued movement of the adjustable rheostat, however, causes the disk to make contact again and the process is repeated. Thus a slow continuous movement of the rheostat adjustment results in a series of intermittent responsive steps in the movement of the contact carriage which are so small in their changes and so close together-in their action that no appreciable flickering occurs in the change of lighting effects.

The function of the reactors 44 will now be explained. When the movable contacts of the Y carriage are` in a position where they make joint connectioni'vith enposed portions of the turns in the two paths, there is an electromotive force due to the portipnf 'fhe auto-transformer winding bridged by the contacts which is imposed upon the local circuit from one set of contacts through the turn of the winding to the other set of contacts. This causes a local exciting current to pass through the reactor windings 44 which, however, serve as chokes to limit the value of this exciting current. The number of turns of the reactor windings and the cross-sectional area of the cores ci these windings are designed such as to limit this exciting current to a desired amount. Also the cores cf these reactors should be proportioned for best results to cause this exciting current to bring the magnetization of the iron of the cores at'or near the knee of the magnetization curve. Under such conditions, although about one-half of the load current may be passing through each oi the reactor windings, the increase in magnetization of the iron due to the load current is comparatively' small and consequently the drop in volts due to the effect of the reactors upon the load circuit is not increased to any objectionable amount. Similarly when only one set of contacts is in engagement with the transformer winding and one reactor only is conducting the full load current the magnetization of the core of this reactor is not appreciably increased beyond the knee of the magnetization curve; consequently the drop in volts due to the comparatively small reactance of this reactor with reference to the full load current is limited to an unobjectionable amount.

Thus it is apparent that the reactors in the local circuit between the contacts serve to limit the local exciting current to an amount which `nor of the contacts.

may be comparatively small so that there is no undue heating of the windings of the transformer; and that these reactors may be designed so that the drop in volts, as regards the load circuit, is not objectionable; and that the reactors may be located apart from the transformer winding so that any heating of the reactors does not affect the heating of the transformer winding It is evident that since the movable contacts do not short-circuit any turn or turns of the transformer winding, there is no necessity of making them of high specific resistance material, as regards the effect of the current in the local circuit of the reactor windings. rThese contacts therefore, as regards these considerations, may be made of metal of high conductivity, such as copper, silver or silver alloy which permits excellent conductive engagement with the turns of the transformer winding while avoidingr heating of the movable contacts.

In passing from a condition where one pairpf Y contacts makes sole connection with the winding to the condition where the other pair of contacts makes sole connection with the winding, the intermediate condition of joint connection to the winding by both sets of contacts gives an additional step of voltage control over that obtained with the usual type of auto-transformer and thereby doubles the number of voltage control stepsV over that obtained in the usual type, because the joint condition of contact provides additional steps by reason of the provision of the reactors. If, however. the voltage drop due to the load current in the reactors is permitted to be undesirably high. the control voltage in passing through successive steps would be irregular. In order to obtain a progressive increase or a progressive decrease in the control voltage in each step, the number of turns of the reactor windings and the cross-sectional area of the cores of these windings are designed not only to limit the exciting current to a desired minimum amount, but the parts are preferably proportioned to cause the exciting current to bring the magnetization of the cores at or near the knee of the magnetization curve, as already explained. This will ordinarily reduce the drop in the reactor windings to such value that an increase or a decrease of the controlled voltage is obtained in passing through each successive stage in the movement of the contacts. In order to obtain this result the drop in volts in each reactor when carrying the full load current should be less than the voltage across adjacent conducting portions of the transformer winding in the path of one of the sets of contacts; and more uniformity of control is obtained in passing through successive steps the smaller the drop in volts due to the load current in the reactors. However, as above explained, sufficient reactance must be provided to insure proper limitation of the current in the local circuit through the reactors when the'contacts are in joint connection with two portions of the winding.

The shunting impedance 54 between the terminals of vthe reactor windings provides a discharge path between its points of connection and serves not only toreduce the arcing at the movable contacts when interrupting connection with a turn of the transformer winding but also serves to permit a discharge current to pass from the reactor which is being disconnected from the load circuit and thereby permits the core of this reactor to approach the condition of non-magnetization in case the interruption of the circuit is made at or near a peak of the alternating magnetization of the core. Thus when the adjustable contacts are moved to cause the reestablishment of the current through this reactor, the iron has in the meantime been conditioned to a point considerably below the peak of magnetization, resulting in a reduction of excessive or undesirable transient current conditions.

Although particular embodiments of this invention have been described, it will be appreciated that the same may be embodied in various forms of structure and that various-modi cations may be made without departing from the scope of the invention.

I claim:

1. An adjustable voltage device for changing the voltage applied to a consumption circuit over a wide range, said device having a movable contact, a screw shaft for adjusting the yposition of said contact, reversible means for driving said shaft, said shaft having a threaded portion of smaller pitch than the main screw of the shaft, a controlling device for said reversible means having a part movable on said threaded portion, and an adjustable remote control device for adjusting the position of another part of said controlling device to thereby cause said movable contact to attain a corresponding position.

2. An adjustable voltage device for changing the voltage applied to a consumption circuit over a wide range, said device having a movable contact, a screw Shaft for adjusting the position of said contact, reversible means for driving said shaft, said shaft having a threaded portion of smaller pitch than the main screw of the shaft, a reversing switch for said reversible means having a part movable on said threaded portion, and

an adjustable remote control device for adjusting the position of another part of said switch to thereby cause said movable contact to attain a corresponding position.

3. An adjustable voltage device for changing the voltage applied to a consumption circuit over a wide range, said device having a movable contact, a screw shaft for adjusting the position of said contact, reversible means for driving said shaft, said shaft having a threaded portion of smaller pitch than the main screw of the shaft, a reversing switch for said reversible means having a part movable on said threaded portion, a solenoid for adjusting the position of another part of said switch, and an adjustable device for adjisting the value of the current in said solenoi y 4. An adjustable voltage device for changing the voltage applied to a consumption circuit over a wide range, said device having a movable contact, a reversible rotary motor, a reversing switch Vfor controlling the direction of rotation of said motor, speed reducing means driven by said mo- 'tor for moving said movable contact in opposite directions at a reduced rate of movement relatively to the motor and for moving' certain of the contacts of said switch at a lower rate of movement relatively to the rate of movement of said movable contact in a direction for opening said switch and thereby opening the circuit of tact, a reversible rotary motor, a reversing switch for controlling the direction of rotation of said motor, speed reducing means driven by said motor for moving said movable contact in opposite directions at a reduced rate of movement relatively to the motor and for moving certain of the contacts of said switch at a lower rate of movementI relatively to the rate of movement of said movable contact in a direction for opening said switch and thereby opening the circuit of said reversible motor, an electrical device for adjusting the position of a contact of said switch for determining the movement and adjusted position of said movable contact, and remote control means for adjusting the current applied to said electrical device.

6. An adjustable voltage device for changing the voltage applied to a consumption circuit over a wide range, said device having a movable contact, a reversible rotary motor, a reversing switch for controlling the direction of rotation of said motor, speed reducing means driven by said motor for moving said movable contact in opposite directions at a reduced rate of movement relatively to the motor and for moving certain of the contacts of said switch at a lower rate of movement relatively to the rate of movement of said movable contact in a direction for opening said switch and thereby opening the circuit of said reversible motor, a solenoid for adjusting the position of a contact of said switch for determining the movement and adjusted position of said movable contact, and remote control means for adjusting the current supplied to said solenoid to different; values corresponding to the desired position of said movable contact.

'7. An adjustable voltage device for changing the voltage applied to a consumption circuit over Y the circuit of said motor; an adjustable remote control device, and means controlled by saldremote control device for moving a contact of said switch to a position corresponding with the adjusted position of saide remote control device and thereby cause said movable contact to attain a. corresponding position.

FRANK G. LOGAN. 

